1. Field of the Invention
The present invention relates to an image forming apparatus and a developing apparatus, in which a developing device develops an electrostatic latent image formed on an image bearing member with powder to form a visible image. Further, the present invention relates to a powder replenishing device that replenishes the developing device with powder contained in a powder container, and a powder conveying device that conveys powder to the developing device.
2. Discussion of the Background
In an image forming apparatus such as a copying machine, a printer, a facsimile, or the like, a toner replenishing device has been used to replenish a developing device with toner contained in a replaceable toner container. In such a toner replenishing device, when all the toner in the toner container is consumed, the toner container is replaced with a new one.
As an example of the above-described toner replenishing device, FIG. 15 illustrates a toner container 111 including a movable member 112 such as a screw and a coil spring. In the toner replenishing device of FIG. 15, the toner in the toner container 111 is conveyed toward a toner discharging outlet (111a) by rotating a rotation shaft (112a) of the movable member 112. Subsequently, the toner is discharged from the toner container 111 through the toner discharging outlet (111a) and is replenished to a developing device.
As another example of the toner replenishing device, FIG. 16 illustrates a screw bottle 211 as a cylindrical toner container. In the screw bottle 211, a protrusion 212 is spirally provided on a circumferential inner surface of the screw bottle 211 along a circumferential direction. The toner in the screw bottle 211 is conveyed toward a toner discharging outlet (211a) by rotating the screw bottle 211. Subsequently, the toner is discharged from the screw bottle 211 through the toner discharging outlet (211a) and is replenished to a developing device.
In the toner container 111 of FIG. 15, because the movable member 112 needs to be provided to discharge the toner from the toner container 111, the total replacement cost for the toner container 111 typically increases. Further, the movable member 112 is driven by a driving source disposed outside of the toner container 111, and an opening for connection is formed with the toner container 111. For this opening, a seal member needs to be provided to seal the opening, thereby increasing complexity of the construction of the toner container 111.
Further, in the screw bottle 211 of FIG. 16, because the protrusion 212 needs to be spirally provided on the circumferential inner surface of the screw bottle 211, the construction of the screw bottle 211 may not be simplified.
Through intense study, the inventors have developed a toner replenishing device that replenishes a developing device with toner contained in a toner container of simple and low-cost construction without a spiral protrusion therein.
The toner replenishing device developed by the inventors employs a rectangular parallelepiped shaped toner container of simple and low-cost construction, and a reciprocating motion device that reciprocates the toner container to move the toner in the toner container toward a toner discharging outlet formed with the toner container. In this toner replenishing device, the toner in the toner container is gradually moved toward the toner discharging outlet by an inertial force of the toner produced when the toner container reciprocates. Then, the toner is discharged from the toner container through the toner discharging outlet.
The above-described toner replenishing device substantially eliminates the problems of the background toner replenishing devices, such as, the complexity of the construction of the toner container and the increase of total replacement cost for the toner container. However, another problem arises in the above-described toner replenishing device, that is, the toner in the toner container may not be properly discharged from the toner container depending on the position of the toner discharging outlet.
Specifically, as illustrated in FIG. 17, when a toner discharging outlet (311a) is formed at a lower part of one end wall of a toner container 311, a toner (T), which is gradually moved toward the one end wall by reciprocating motions of the toner container 311, cumulates around the toner discharging outlet (311a) after the toner (T) has hit against the one end wall. Thereafter, the cumulated toner (T) is typically compressed by gravity. As a result, the compressed toner (T) may block the toner discharging outlet (311a), and a toner replenishing amount may be decreased due to production of an aggregated toner mass larger than the toner discharging outlet (311a). Thus, the toner (T) may not be properly discharged from the toner container 311.
The above-described problems of the toner replenishing device may also occur in a powder replenishing device that replenishes a developing device with powder contained in a powder container by reciprocating the powder replenishing device.
As a technology relating to the present invention, Japanese Laid-open Patent Publication No. 9-244372 describes a toner feeding device. The contents of this reference are incorporated herein by reference in their entirety. This device includes a replaceable toner container, an engaging device which engages the toner container with the toner feeding device, and a reciprocating oscillation supplying device that supplies the reciprocating oscillation to the toner container so as to move a toner in the toner container toward a toner discharging outlet. Further, in the toner feeding device, grooves orthogonal to the direction of the reciprocating oscillation are provided on an inner wall of the toner container.
Moreover, in the toner feeding device of JP9-244372, the toner discharging outlet is formed at an upper part of one end wall of the toner container, and a plurality of grooves are provided on the inner wall of the toner container which inclines upwardly toward the toner discharging outlet. The toner in the toner container climbs over each groove and is moved to the toner discharging outlet by the reciprocating oscillation of the toner container.
In the toner feeding device thus constructed, because the toner is neither cumulated nor compressed around the toner discharging outlet, problems, such as an occurrence of blockage in a toner discharging outlet due to a compressed toner, and a decrease of toner replenishing amount due to production of an aggregated toner mass larger than a toner discharging outlet, are prevented.
On the other hand, because the above-described toner feeding device has a special construction such as a plurality of grooves on the inner wall of the toner container, the construction of the toner container is complex, so that a total replacement cost for the toner container increases.
In addition to the toner replenishing device, the inventors have developed a toner conveying device that conveys toner to a developing device. The toner conveying device includes a toner conveying path member forming a toner conveying path having an inlet and an outlet. The toner conveying path member is disposed such that a bottom surface of the toner conveying path member is in substantially a horizontal position. The toner conveying device further includes a reciprocating motion device that reciprocates the toner conveying path member in substantially a horizontal direction so as to move the toner in the toner conveying path member toward the outlet.
In the toner conveying device thus constructed, the toner in the toner conveying path member is gradually moved toward the outlet of the toner conveying path member by an inertial force of the toner in the toner conveying path member produced when the toner conveying path member reciprocates. Then, the toner is conveyed to the developing device through the outlet.
For reducing the size of the toner conveying device thus constructed, the size of the toner conveying path member is desired to be small. Further, for reducing the size of the toner conveying path member, the toner conveying path member should be constructed such that a cross-sectional area of the toner conveying path member in a direction perpendicular to the toner conveying direction is small.
However, as the cross-sectional area of the toner conveying path member in a direction perpendicular to the toner conveying direction becomes smaller, the contact area of toner with the toner conveying path member increases on condition that the toner conveying amount is held constant. The increase of the contact area of toner with the toner conveying path member causes a frictional resistance between the toner and the toner conveying path member to increase. As a result, the toner in the toner conveying path member may not be smoothly conveyed toward the outlet.
The above-described problem of the toner conveying device may also occur in a powder conveying device that conveys powder in a powder conveying path member to a developing device by reciprocating the powder conveying path member.
According to one aspect of the present invention, a powder replenishing device includes a powder container configured to contain powder, the powder container includes a powder discharging outlet at one end portion of one side wall of the powder container. The powder replenishing device further includes a reciprocating motion device configured to reciprocate the powder container between forward and backward directions with respect to a moving direction of the powder toward the powder discharging outlet so as to move the powder in the powder container toward the powder discharging outlet in a state that the powder discharging outlet is directed downward in substantially a vertical direction.
According to another aspect of the present invention, a powder conveying device includes a powder conveying path member configured to convey powder therethrough. The powder conveying path member includes one side wall and forms a powder conveying path having an inlet and an outlet. The outlet is directed downward in substantially a vertical direction. The powder conveying device further includes a reciprocating motion device configured to reciprocate the powder conveying path member between forward and backward directions with respect to a moving direction of the powder toward the outlet so as to move the powder in the powder conveying path member toward the outlet. The powder conveying path member is provided such that the one side wall inclines downwardly toward the outlet.
According to another aspect of the present invention, a method of replenishing powder to a developing device of an image forming apparatus includes containing the powder in a powder container having a powder discharging outlet, and reciprocating the powder container between forward and backward directions with respect to a moving direction of the powder toward the powder discharging outlet so as to move the powder in the powder container toward the powder discharging outlet.
According to another aspect of the present invention, a method of conveying powder through a powder conveying path member having an outlet to a developing device of an image forming apparatus, includes reciprocating the powder conveying path member between forward and backward directions with respect to a moving direction of the powder toward the outlet so as to move the powder in the powder conveying path member toward the outlet, and falling the powder through the outlet to the developing device.
Objects, features, and advantages of the present invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings.